Reference Design For Power Supply; Monitor The Power Supply - Quectel EG91 Series Hardware Design

LTE Standard Module Series
EG91 Series Hardware Design
VBAT
VBAT_RF
VBAT_BB
+
+
C5
C3 C4 C6 C7 C8
C2
C1
D1
100nF 10pF
33pF 100uF 100nF 33pF 10pF
100uF
WS4.5D3HV
Module
Figure 8: Star Structure of Power Supply

3.6.3. Reference Design for Power Supply

Power design for the module is very important, as the performance of the module largely depends on the
power source. The power supply should be able to provide sufficient current up to 2A at least. If the
voltage drop between the input and output is not too high, it is suggested that an LDO should be used to
supply power for the module. If there is a big voltage difference between the input source and the desired
output (VBAT), a buck converter is preferred to be used as the power supply.
The following figure shows a reference design for +5V input power source. The typical output of the power
supply is about 3.8V and the maximum load current is 3A.
Figure 9: Reference Circuit of Power Supply

3.6.4. Monitor the Power Supply

AT+CBC command can be used to monitor the VBAT_BB voltage value. For more details, please refer to
document [2].
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